Method and apparatus for forming insitu boron doped polycrystalline and amorphous silicon films

ABSTRACT

A method and apparatus for depositing a boron insitu doped amorphous or polycrystalline silicon film on a substrate. According to the present invention, a substrate is placed into deposition chamber. A reactant gas mix comprising a silicon source gas, boron source gas, and a carrier gas is fed into the deposition chamber. The carrier gas is fed into the deposition chamber at a rate so that the residence of the carrier gas in the deposition chamber is less then or equal to 3 seconds or alternatively has a velocity of at least 4 inches/sec. In another embodiment of forming a boron doped amorphous for polycrystalline silicon film a substrate is placed into a deposition chamber. The substrate is heated to a deposition temperature between 580-750° C. and the chamber pressure reduced to a deposition pressure of less than or equal to 50 torr. A silicon source gas is fed into the deposition at a rate to provide a silicon source gas partial pressure of between 1-5 torr. Additionally, a boron source gas is fed into the deposition chamber at a rate to provide a boron gas partial pressure of between 0.005-0.05 torr.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to the field of thin film formation, andmore particularly to a method and apparatus for depositing an insituboron doped amorphous or polycrystalline silicon film.

2. Discussion of Related Art

Polycrystalline silicon (polysilicon) and amorphous silicon thin filmsare used throughout the many semiconductor integrated circuitmanufacturing processes. These films are used, for example, in thefabrication of gate electrodes, stack or trench capacitors, emitters,contacts, fuses, and antifuses. As device dimensions decrease to below0.25 microns in order to increase packing density, aspect ratios (aspectratio=depth/width) of holes, vias, and trenches in the integratedcircuit are also increasing. In order to fill high aspect ratio openings(aspect ratios ≧ to 2.5), deposition processes which are capable of goodstep coverage (step coverage %=film thickness on a step surface/filmthickness on a flat surface×100%) are required to ensure complete holefilling without the creation of voids.

One current method which can provide adequate step coverage is lowpressure chemical vapor deposition (LPCVD). In LPCVD processes, reactionvessels are evacuated to relatively low pressures of between 100-1000 mtorr. The low pressures associated with LPCVD processes cause siliconfilms to be deposited at low rates (about 100 angstroms (Å)/minute forundoped films and about 20 Å/minute for doped films). The low depositionrates enable the films to be deposited with good step coverage. Whenn-type dopants are introduced in a LPCVD batch system to produce aninsitu doped film, step coverage decreases. A further reduction in thedeposition rate is necessary for good step coverage. Although LPCVDprocesses can form high quality films, their low deposition ratesnecessitate the processing of multiple wafers (i.e. up to 100) at onetime in a batch type reaction vessel. A problem with processing aplurality of wafers in a single machine at a single time is that it isdifficult to obtain uniform thickness film and dopant concentration fromwafer to wafer and from batch to batch.

To fabricate polysilicon and amorphous silicon films with precisethickness and doping uniformity across a wafer and from wafer to wafer,single wafer CVD processes are used. A single wafer CVD process forproducing a silicon layer on a silicon wafer is described in U.S. Ser.No. 07/742,954, filed Aug. 9, 1991, entitled Low Temperature HighPressure Silicon Deposition Method and is assigned to the presentassignee. Such a single wafer reactor can reliably form a uniformsilicon film which is insitu doped with n type dopants (e.g. arsenic andphosphorus).

At times, however, such as in the manufacture of Flash memory devicesand p channel devices, it is desireable to form amorphous orpolycrystalline films which are insitu doped with p type dopants (e.g.boron).

Thus, what is desired is a method and apparatus which enables an insituboron doped polycrystalline or amorphous silicon film to be deposited ina single wafer reactor without forming deposits on the chamber windowsand liners.

SUMMARY OF THE INVENTION

A method and apparatus for depositing an insitu boron doped amorphous orpolycrystalline silicon film on a substrate. According to the presentinvention, a substrate is placed into a deposition chamber. A reactantgas mix comprising a silicon source gas, a boron source gas, and acarrier gas are fed into the deposition chamber. The reactant gas mix isfed into the deposition chamber at a rate so that the residence time ofthe reactant gas in the deposition chamber is less then or equal to 3seconds or alternatively has a velocity of at least 4 inches/sec.

In another embodiment of the present invention an insitu boron dopedamorphous and polycrystalline silicon film, a substrate is placed into adeposition chamber. The substrate is then heated to a depositiontemperature between 580-750° C. and the chamber pressure reduced to lessthan or equal to 50 torr. A silicon source gas is then fed into thedeposition at a rate to provide a silicon source gas partial pressure ofbetween 1-5 torr while a boron source gas is fed into the depositionchamber at a rate to provide a boron source gas partial pressure ofbetween 0.005-0.05 torr.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is an illustration of a cross sectional view of a substrate onwhich the insitu boron doped silicon film of the present invention canbe formed.

FIG. 1B is an illustration of a cross-sectional view showing theformation of a insitu boron doped silicon film on the substrate of FIG.1A.

FIG. 2 is a flowchart which illustrates a method of forming an insituboron doped amorphous or polycrystalline silicon film in accordance withthe present invention.

FIG. 3A is an illustration of a single wafer thermal chemical vapordeposition apparatus which can be used to deposit the insitu boron dopedamorphous or polycrystalline silicon film of the present invention.

FIG. 3B is an illustration of a system control computer program whichcan be used to control the thermal chemical vapor deposition apparatusof FIG. 3A to form an insitu boron doped amorphous or polycrystallinesilicon film.

FIG. 4 is a graph which illustrates how the resitivity of an insituboron doped polycrystalline film decreases with increasing carrier gasflow.

DETAILED DESCRIPTION OF THE PRESENT INVENTION

The present invention describes a novel method and apparatus fordepositing an insitu boron doped polycrystalline or amorphous siliconfilm. In the following description, numerous specific details are setforth such as specific process parameters and implementation in order toprovide a thorough understanding of the present invention. It will beobvious, however, to one skilled in the art, that the present inventionmay be practiced without the specific details. In other instances, wellknown chemical vapor deposition (CVD) equipment and semiconductormethodology have not been described in particular detail in order to notnecessarily obscure the present invention.

The present invention describes a method and apparatus for depositing aninsitu boron doped polycrystalline or amorphous silicon film at a highdeposition rate and with good step coverage. According to the presentinvention, a substrate (or wafer) is placed into a deposition chamber ofa thermal chemical vapor deposition (CVD) apparatus. The pressure in thedeposition chamber is then reduced to a deposition pressure of less thanor equal to 50 torrs and the substrate heated to a depositiontemperature of greater than or equal to 580° C. A reactant gas mixcomprising a silicon containing gas, such as but not limited to silane(SiH₄), a boron containing gas, such as but not limited to diborane,(B₂H₆) and a carrier gas, such as but not limited to hydrogen (H₂) andhelium (He) is fed into the deposition chamber. Heat from the substratecauses the silicon containing gas to disassociate and provide siliconatoms and causes the diborane to disassociate and provide boron atoms. Apolycrystalline or amorphous silicon film doped insitu with boron atomsis then deposited on to the substrate from the silicon atoms and theboron atoms.

The present invention uses a combination of low deposition pressure(less than 50 torr) and high carrier gas flow (greater than 10 SLM) toform the insitu boron doped amorphous or polycrystalline silicon film ofthe present invention. The combination of low deposition pressure andhigh carrier gas flow enables the formation of a silicon film with ahigh boron concentration of (up to 4×10²⁰ atoms/cm³) at a highdeposition rate (greater than 1000 Å/min). Additionally, the combinationof low deposition pressure and high carrier gas flow dramaticallyreduces film formation on the domes (windows) and on the sidewall linerof the CVD apparatus. By preventing film formation on the domes, filmuniformity from wafer to wafer is dramatically improved. Additionally,by reducing film formation on the windows and liners, more wafers can beprocessed before cleaning is required thereby reducing the cost of thedeposition process.

The insitu boron doped amorphous or polycrystalline silicon film of thepresent invention can be formed on a substrate, such as semiconductorsubstrate 100, shown in FIG. 1A. Substrate 100 is preferably amonocrystalline silicon wafer. Substrate 100, however, need notnecessarily be a silicon wafer, and may be other types of substratessuch as a gallium arsenide or a germanium silicon substrate orsubstrates used for other purposes. Substrate 100 typically will includea plurality of spaced apart features or holes 102. Features 102 can bedue to, but not limited to, trenches formed in a substrate, field oxideregions formed on a substrate, and contact/via openings formed in aninterlayer dielectric (ILD). The process of the present invention isideally suited for depositing a high concentration (>5×10¹⁹ atoms/cm³)boron doped silicon film into a high aspect ratio opening (greater than2:1) during the formation of capacitors and/or contacts in themanufacturer of modern high density dynamic random access memories(DRAM) and other integrated circuits. Although the present invention isideally suited for use in manufacturer of integrated circuits, thepresent invention is equally applicable to the formation of otherproducts. For the purposes of the present invention, substrate 100 isdefined as a material onto which the insitu boron doped amorphous orpolycrystalline silicon film of the present invention film is deposited.

The method of the present invention will be described and illustratedwith respect to the flowchart 200 of FIG. 2. The first step of thepresent invention as set forth in block 202 of flowchart 200 is to placea substrate, such as substrate 100, into a deposition chamber of athermal chemical vapor deposition apparatus, such as a single substratereactor 300 shown in FIG. 3A. The single substrate reactor 300 shown inFIG. 3A has a top quartz window (or dome) 312, sidewalls 314 and abottom quartz window (or dome) 318 that define a chamber 319 into whicha single wafer or substrate 100 can be located. The interior ofsidewalls 314 are covered by a quartz liner. Chamber 319 is designed tohandle wafers up to 200 mm and has a volume of approximately 10 liters.An example of such a reactor is the Applied Materials Centura SingleWafer Chamber Tool. It is to be appreciated that larger volume chambersfor handling larger wafers such as 300 mm, may be used if desired.Additionally, all flow rates provided herein are with respect to a 10liter chamber and one skilled in the art will recognize the ability toscale flow rates for different volume chambers if desired. What isimportant is to utilize the partial pressures of the gases providedherein.

Substrate 100 is mounted on a pedestal or susceptor 322 that is rotatedby a motor (not shown) to provide a time average environment forsubstrate 100 that is cylindrically symmetric. A susceptorcircumscribing preheat ring 324 supported by sidewall 314 and surroundssusceptor 322 and substrate 100. Lifting fingers 323 pass through holes(not shown) formed through susceptor 322 to engage the underside ofsubstrate 100 to lift it off susceptor 322. Substrate 100, preheat ring324, and susceptor 322 are heated by light from a plurality of highintensity lamps 326 mounted outside of reactor 300. High intensity lamps326 are preferably tungsten halogen lamps which produce infrared (IR)light at a wavelength of approximately 1.1 microns. The top 312 andbottom 318 of reactor 310 are substantially transparent to light toenable light from external lamps 326 to enter reactor 310 and heatsusceptor 322, substrate 100 and preheat ring 324. Quartz is preferablyused for the top 312 and bottom 318 because it is transparent to lightof a visible and IR frequency; because it is relatively high strengthmaterial that can support a large pressure difference across; andbecause it has a low rate of outgassing. A suitable top temperaturesensor 340 and a suitable bottom temperature sensor 342 such aspyrometers are positioned to measure the temperature of substrate 100and a temperature of susceptor 322, respectively. Although a lamp heatedchamber is desired, the present invention can be carried out in othertypes of thermal CVD chambers such as resistance heated chambers.Additionally, although reactor 300 typically includes a single wafer itis possible to size susceptor 322 sufficiently to position multiplewafers face up on susceptor 322. Apparatus 300 includes a systemcontroller 350 which controls various operations, of apparatus 300 suchas controlling gas flows, substrate temperature, and chamber pressure.

Next, according to block 204 of FIG. 2, chamber 319 is evacuated throughexhaust port 332 by a pump 344 to reduce the pressure in chamber 319from atmospheric pressure to deposition pressure. The depositionpressure is the total pressure within chamber 319 when a insitu borondoped amorphous or polycrystalline silicon film of the present inventionis deposited. The deposition pressure of the present invention isbetween 10-50 torr. The low deposition pressure helps prevent domecoating and provide good step coverage.

Next, as set forth in block 206, of flowchart 200 substrate 100, preheatring 324 and susceptor 322 are heated by lamps 326 to the depositiontemperature. The deposition temperature of the present invention is atleast 580° C. and preferably between 600-750°C. It is to be appreciatedthat the exact crystalline structure of the deposited silicon filmdepends upon the deposition temperature. In order to deposit anamorphous silicon film which is insitu doped with boron atoms thedeposition temperature should be between 580-620° C. In order to deposita polycrystalline silicon film which is insitu doped with boron atomsthe deposition temperature should be greater than 620° C.

Next, as set forth in block 208 of flowchart 200, a reactant gas mix isfed into reaction chamber 319. According to the present invention thereactant gas mix comprises a silicon containing gas, such as but notlimited to silane (SiH₄) and disiline (Si₂H₆), a boron source, such asbut not limited to diborane (B₂H₆), and a carrier gas such as but notlimited to hydrogen (H₂), Helium (He), and nitrogen (N₂). The depositionpressure and temperature are maintained within the specified rangeswhile the reactant gas mix flows into reaction chamber 319 to depositand insitu boron doped amorphous or polycrystalline silicon film 104 onsubstrate 100 as shown in FIG. 1B and set forth in block 210 offlowchart 200.

During deposition, the reactant gas mix stream flows from gas input 328across preheat ring 324 where the gases are heated, across substrate 100in the direction of arrows 330 to deposit and insitu boron dopedamorphous or polycrystalline silicon film 104 thereon and out throughexhaust port 332. The gas input port 328 is connected, via conduit 334to a gas supply represented by tanks 336 that provides one or a mixtureof gases. The gas concentration and/or flow rate through conduit 334 andeach of the ports 328 and 332 are selected to produce processing gasflows and concentration profiles that optimize processing uniformity.Although the rotation of the substrate 100 in the thermal gradientscaused by heat lamp 326 can significantly affect the flow of gases inreactor 300 the dominant shape of flow profile is laminar flow from gasinput port 328 across preheat ring 324 and substrate 100 to exhaust port332.

According to an embodiment of the present invention, the siliconcontaining gas is provided into the deposition chamber 319 at a flowrate between 200-1000 SCCM to produce a silicon containing gas partialpressure of between 1-5 torr and preferably between 1.5-2.5 torr.Diborane (B₂H₆) is fed into the deposition chamber of between 0.5-2.0SCCM to produce a diborane partial pressure of between 0.005-0.05 torr.Diborane is preferably diluted with a carrier gas, such as H₂ to form a1% diluted diborane dopant gas (i.e. diluted diborane equals 1% diboraneand 99% carrier gas) in order to enable better control of the amount ofdiborane which is provided into reaction chamber 319. As such, when a 1%diluted diborane dopant gas is utilized it is fed into the chamber at arate of between 50-200 SCCM in order to produce a diborane partialpressure of between 0.005-0.05 torr. The amount of diborane providedinto chamber 319 during the deposition is less than 1% of the amount ofsilicon containing gas provided into the chamber during deposition. Thesilicon containing gas and the diluted diborane are combined with acarrier gas, such as H2, outside of reaction chamber 319 to form thereactant gas mix. The carrier gas transports the silicon containing gasand the diluted diborane dopant gas into chamber 319.

According to present invention a large carrier gas flow rate of at least10 SLM and preferably between 10-15 SLM is used, such a large carriergas flow rate produces a carrier gas partial pressure of between 9-48torr. It has been found that increasing the carrier gas flow increasesthe amount of boron which is incorporated into the deposited amorphousor polycrystalline silicon film for a fixed boron flow. By utilizing ahigh carrier gas flow a relatively small amount of diborane is needed inthe ambient to achieve a relatively high boron concentration (at least5×10¹⁹ atoms/cm³ and up to 4×10²⁰ atoms/cm³) into the deposited film.FIG. 4 is a graph which illustrates how under constant conditions theresistivity of a polycrystalline silicon film insitu doped with boronatoms decreases with increasing carrier gas flow. It has been found thatdiborane assists in the decomposition of the silicon source gas intosilicon atoms. Increasing the disassociation of the silicon source gasleads to an increase in silicon deposition and an increase of silicondeposition on the walls of the chamber 319 and on the quartz windows 312and 318. By reducing the amount of diborane in the chamber duringdeposition, film deposition on the sidewalls and on the quartz windowsis dramatically reduced.

Another benefit of the high carrier gas flow used in the presentinvention is that the boundary layer of the laminar flow of the reactantgas mix is decreased. By lowering the boundary layer of the reactant gasmix, the chance of film deposition on the top and bottom quartz windows312 and 318 is dramatically reduced.

Additionally, the use of a low deposition pressure during the formationof an insitu boron doped amorphous or silicon film helps to reduce domecoating. Although the present invention uses a low deposition pressure,a silicon film having a boron doping density of up to 4×10²⁰/atoms/cm³can still be formed at a relatively high deposition rate of greater than1000 Å/min. The high deposition rate is due to the fact that diboraneassists in the disassociation of the silicon source gas into siliconatoms. Additionally, the low deposition pressure enables the formationof an insitu boron doped amorphous or polycrystalline silicon film withgood step coverage which in turn allows the film to fill in high aspectratio openings of greater than 2:1 without forming voids therein.

It has been found that what is important in order to achieve an insituboron doped silicon film having a high boron concentration withoutexcessive film deposition on chamber windows and sidewalls, is toutilize process conditions so that the residence time of the reactantgas mix through the chamber is low, less than or equal 3.0 seconds andpreferably less than 2 seconds. That is, an embodiment of the presentinvention the flow rate of the reactant gas mix, the pump speed, and thedeposition pressure within the chamber are controlled or chosen so thatthe amount of time it takes for the reactant gas mix flow from theinterior sidewall near gas inlet 328 to the interior sidewall near gasoutlet 322 is less than or equal to 3 seconds and preferably less than 2seconds.

The residence time (t_(res)) of the reactant gas mix inside chamber 319is:

$\begin{matrix}{t_{res} = \frac{V_{ch}}{Q}} & \text{eq.~~(1)}\end{matrix}$

where Vch=chamber volume (liters) and where Q is the gas flow rate outof the chamber (i.e., pumping speed (liters/sec)). The ideal gasequation states:

$\begin{matrix}{\frac{P\quad V}{T} = \frac{P_{STD} \cdot V_{STD}}{T_{STD}}} & \text{eq.~~(2)}\end{matrix}$

where T_(STD=)273° K, P_(STD=)760 Torr. Transforming equation (2) toflow rates yields:

$\begin{matrix}{\frac{P_{STD}Q_{STD}}{T_{STD}} = \frac{P\quad Q}{T}} & \text{eq.~~(3)}\end{matrix}$

where Q_(STD) is the reactant gas flow rate into the chamber, and Q isthe gas flow rate out from the chamber (pumping speed (liter/sec)) and Tis the deposition temperature (K°) and P is the deposition pressure(Torr). Equation (3) can be solved for Q and substituted into eq (1) toyield:

$\begin{matrix}{t_{res} = \frac{{V_{ch} \cdot T_{STD}}P}{{T \cdot P_{STD}}Q_{STD}}} & \text{eq. (4)}\end{matrix}$

It is to be appreciated that all gas molecules do the turbulence causedby the walls and domes etc. will not exhibit the same residence time inthe chamber. However, equation 4 does provide a sufficiently accuratemeans for determining the typical residence time of gas within thechamber. As such, in an embodiment of the present invention the reactantgas has a residence time of less than or equal to 3 seconds andpreferably less than or equal to 2 seconds as calculated by equation 4.

Alternative to the residence time of the reacting gas, one can look atthe velocity of the reactant gas as it flows from the gas input to thegas output of the chamber. For example, in the case when reactor 300 isconfigured to process a 200 mm wafer (8 inch) the total distance fromthe interior of sidewall 314 of gas inlet 328 to the interior ofsidewall 314 at gas outlet 332 is approximately 12 inches. Assuming therequired residence time of less than 3 seconds and preferably less than2 seconds yields necessary reactant gas velocity of at least 4inches/sec. and preferably at least 6 inches/sec.

Hydrogen (H₂) is preferred as the carrier gas and as the dilution gas inthe present invention because an ambient comprising a large amount of H₂can withstand a large thermal gradient. In this way, the temperature ofquartz windows 312 and 318 and sidewall 314 can be maintained at atemperature significantly lower then the temperature of substrate 100during film deposition. By keeping the temperature of windows 312 and318 and sidewall 314 low, film deposition or coating on the windows andsidewall is substantially reduced. Additionally by reducing filmdeposition on sidewalls 314 and windows 312 and 318 more wafers can beprocessed before cleaning is required.

Next as shown in block 212, substrate 100 can be annealed if desired.Substrate 100 can be annealed in order to convert an as deposited insituboron doped amorphous silicon or amorphous/polycrystalline silicon filminto a low resistance insitu doped polycrystalline silicon film. In thisway, an amorphous silicon film can be deposited at a relatively lowtemperature in order to improve step coverage of the film and ensurecomplete hole filling and subsequently be converted by annealing into alow resistance polycrystalline silicon germanium film. Any well knownmethod and equipment can be utilized to anneal substrate 100. Forexample, substrate 100 can be annealed in a furnace at a temperaturegreater than or equal to 800° C. for 30 minutes in a nitrogen/oxygenambient. Alternatively, a rapid thermal anneal (RTA) at temperatureabout 1000° C. for less than 15 seconds in a nitrogen/oxygen ambient canbe used. Although annealing substrate 100 requires an additional stepmany integrated circuit manufacturing processes, such as DRAM processes,require subsequent anneals for other purposes such as silicide formationand so the anneal step can be included without affecting throughput.Utilizing the anneal step of the present invention allows a lowresistance insitu boron doped polycrystalline silicon film to be formedin high aspect ratio openings without void formation.

The process of the present invention can form a high quality insituboron doped polycrystalline or amorphous silicon film with a high dopantdensity (5×10¹⁹⁻4×10²⁰ atoms/cm³) and therefore a low resistivity (aslow as 1.0 mohm-cm) at a high deposition rate (between 600 Å/min-1,200Å/min) and with excellent step coverage (above 90%). The presentinvention can be reliably used to fill openings in a substrate 100having a width less than 0.28 microns and an aspect ratio greater than2.0 at a high deposition rate without creating voids therein.

In a embodiment of the present invention the system controller 350includes a hard disk drive (memory 352), a floppy disk drive and aprocessor 354. The processor contains a single board computer (SBC),analog and digital input/output boards, interface boards and steppermotor controller board. Various parts of CVD system 300 conform to theVersa Modular Europeans (VME) standard which defines board, card cage,and connector dimensions and types. The VME standard also defines thebus structure having a 16-bit data bus and 24-bit address bus.

System controller 350 controls all of the activities of the CVD machine.The system controller executes system control software, which is acomputer program stored in a computer-readable medium such as a memory352. Preferably, memory 352 is a hard disk drive, but memory 352 mayalso be other kinds of memory. The computer program includes sets ofinstructions that dictate the timing, mixture of gases, chamberpressure, chamber temperature, lamp power levels, susceptor position,and other parameters of a particular process. Of course, other computerprograms such as one stored on another memory device including, forexample, a floppy disk or other another appropriate drive, may also beused to operate controller 350. An input/output device 356 such as a CRTmonitor and a keyboard is used to interface between a user andcontroller 350.

The process for depositing the film can be implemented using a computerprogram product which is stored in memory 352 and is executed bycontroller 350. The computer program code can be written in anyconventional computer readable programming language, such as, 68000assembly language, C, C++, Pascal, Fortran, or others. Suitable programcode is entered into a single file, or multiple files, using aconventional text editor, and stored or embodied in a computer usablemedium, such as a memory system of the computer. If the entered codetext is in a high level language, the code is compiled, and theresultant complier code is then linked with an object code ofprecompiled windows library routines. To execute the linked compiledobject code, the system user invokes the object code, causing thecomputer system to load the code in memory, from which the CPU reads andexecutes the code to perform the tasks identified in the program. Alsostored in memory 352 are process parameters such as reactant gas flowrates and composition, temperatures and pressure necessary to carry outthe deposition of an insitu boron doped amorphous or polycrystallinesilicon film in accordance with the present invention.

FIG. 3B illustrates an example of the hierarchy of the system controlcomputer program stored in memory 352. The system control programincludes a chamber manager subroutine 370. The chamber managersubroutine 370 also controls execution of various chamber componentsubroutines which control operation of the chamber components necessaryto carry out the selected process set. Examples of chamber componentsubroutines are reactant gas control subroutine 372, pressure controlsubroutine 374 and a lamp control subroutine 376. Those having ordinaryskill in the art would readily recognize that other chamber controlsubroutines can be included depending on what processes are desired tobe performed in the process chamber 319. In operation, the chambermanager subroutine 370 selectively schedules or calls the processcomponent subroutines in accordance with the particular process setbeing executed. Typically, the chamber manager subroutine 370 includessteps of monitoring the various chamber components, determining whichcomponents needs to be operated based on the process parameters for theprocess set to be executed and causing execution of a chamber componentsubroutine responsive to the monitoring and determining steps.

The reactant gas control subroutine 372 has program code for controllingreactant gas composition and flow rates. The reactant gas controlsubroutine 372 controls the open/close position of the safety shut-offvalves, and also ramps up/down the mass flow controllers 337 to obtainthe desired gas flow rate. The reactant gas control subroutine 372 isinvoked by the chamber manager subroutine 370, as are all chambercomponent subroutines and receives from the chamber manager subroutineprocess parameters related to the desired gas flow rates. Typically, thereactant gas control subroutine 372 operates by opening the gas supplylines, and repeatedly (i) reading the necessary mass flow controllers,(ii) comparing the readings to the desired flow rates received from thechamber manager subroutine 370, and (iii) adjusting the flow rates ofthe gas supply lines as necessary. Furthermore, the reactant gas controlsubroutine 372 includes steps for monitoring the gas flow rates forunsafe rates, and activating the safety shut-off valves when an unsafecondition is detected.

The pressure control subroutine 376 comprises program code forcontrolling the pressure in the chamber 319 by regulating the size ofthe opening of the throttle valve is set to control the chamber pressureto the desired level in relation to the total process gas flow, size ofthe process chamber, and pumping setpoint pressure for the exhaustsystem. When the pressure control subroutine 374 operates to measure thepressure in the chamber 319 by reading one or more conventional pressurenanometers connected to the chamber, compare the measure value(s) to thetarget pressure, obtain PID (proportional, integral, and differential)values from a stored pressure table corresponding to the targetpressure, and adjust the throttle valve according to the PID valuesobtained from the pressure table. Alternatively, the pressure controlsubroutine 374 can be written to open or close the throttle valve to aparticular opening size to regulate the chamber 319 to the desiredpressure.

The lamp control subroutine 376 comprises program code for controllingthe power provided to lamps 326 which is used to heat the substrate 100.The lamp control subroutine 376 is also invoked by the chamber managersubroutine 370 and receives a target, or setpoint, temperatureparameter. The lamp control subroutine 376 measures the temperature bymeasuring voltage output of the temperature measurement devices directedat the susceptor 322 compares the measured temperature to the setpointtemperature, and increases or decreases power applied to the lamps toobtain the setpoint temperature.

Thus, a method and apparatus for depositing an insitu boron dopedamorphous or polycrystalline film which reduces dome and liner coatinghas been described.

What is claimed is:
 1. A method for forming a boron doped amorphoussilicon film or a boron adoped polycrystalline silicon film comprising:generating a deposition pressure within a chamber of between 10-50 torr;heating a substrate in said deposition chamber to a temperature greaterthan or equal to 580° C.; providing a reactant gas mix into saiddeposition chamber, said reactant gas mix comprising a silicon sourcegas, a boron source, and a carrier gas while heating said substrate; andwherein the residence time of said reactant gas mix in said depositionchamber is less than or equal to 3.0 seconds.
 2. The method of claim 1wherein said carrier gas is hydrogen.
 3. The method of claim 2 whereinsaid hydrogen gas is fed into said deposition chamber at a rate greaterthan 10 slm.
 4. The method of claim 1 wherein said residence time ofsaid reactant gas mix is less than 2.0 seconds in said chamber.
 5. Themethod of claim 1 wherein said silicon source gas has a partial pressureof between 1-5 torr in said deposition chamber.
 6. The method of claim 1wherein said silicon source gas has a partial pressure of between1.5-2.5 torr in said deposition chamber.
 7. The method of claim 1wherein said boron source has a partial pressure of between 0.005-0.05torr in said deposition chamber.
 8. The method of claim 1 wherein saidboron source has a partial pressure of between 0.015-0.025 torr in saiddeposition chamber.
 9. A method of forming an insitu boron dopedamorphous silicon film or an insitu boron doped polycrystalline siliconfilm comprising: generating a pressure in a deposition chamber; heatinga substrate to a temperature greater than 580° C. in said depositionchamber; flowing a reactant gas mix comprising a silicon source gas,diborane, and a carrier gas into said deposition chamber while heatingsaid substrate; and controlling the pressure, the temperature, and theflow rate of said reactant gas mix into said deposition chamber so thatsaid reactant gas mix has a residence time in said chamber of less thanor equal to 3.0 seconds.
 10. A method of claim 9 wherein said residencetime is less than or equal to 2.0 seconds.
 11. The method of claim 9wherein said flow of said reactant gas mix is greater than or equal to10 slm.
 12. The method of claim 9 wherein said pressure is less than orequal to 50 torr.
 13. The method of claim 9 wherein said carrier gas isHydrogen.
 14. A method of forming a boron doped amorphous silicon filmor a boron doped polycrystalline silicon film comprising: heating asubstrate to a temperature between 580-750° C. in a deposition chamber;generating a pressure of less than or equal to 50 torr in saiddeposition chamber; providing a silicon source gas into said depositionchamber, wherein said silicon source gas has a partial pressure ofbetween 1-5 torr; providing diborane into said deposition chamber,wherein said diborane has a partial pressure of between 0.005-0.05 torrin said deposition chamber; and providing a hydrogen carrier gas intosaid deposition chamber wherein said hydrogen carrier gas has a partialpressure of between 9-48 torr in said deposition chamber.
 15. The methodof claim 14 wherein the pressure is between 10-50 torr.
 16. The methodclaim 15 wherein said pressure is approximately 40 torr.
 17. The methodof claim 16 wherein said hydrogen carrier gas is fed into saiddeposition chamber at a rate greater than 10 slm.
 18. The method ofclaim 17 wherein said flow rate of said hydrogen gas is between 10-15slm.
 19. The method of claim 18 wherein said flow rate of said hydrogengas is approximately 12 slm.
 20. A method for forming a boron dopedamorphous silicon film or a boron doped polycrystalline silicon filmcomprising: placing a substrate in a deposition chamber, heating saidsubstrate to a temperature greater than or equal to 580° C.; providing areactant gas mix into a chamber, said reactant gas mix comprising asilicon source gas, a boron source, and a carrier gas into a depositionchamber; and wherein the velocity of said reactant gas mix in saiddeposition chamber is greater than or equal to 4 inches/sec.